Recently, the research group of Prof. Huang Rongfeng from Biotechnology Research Institute, Chinese Academy of Agricultural Sciences (BRI, CAAS) has dissected the molecular mechanism of the coordination of ABA and auxin in controlling rice root growth in response to soil compaction, which provides new avenues for breeders to select crops resilient to soil compaction. The results are published on Plant Physiology with the title of “Abscisic acid promotes auxin biosynthesis to inhibit primary root elongation in rice”.

Soil compaction reduces crop yield by 25%. Plants with roots that are able to penetrate hard soil have the advantage in water and nutrient capture at depth, ultimately affording superior performance under drought or low soil fertility. Therefore, dissecting the molecular mechanism of soil compaction restricting root growth will help us improve the performance of crops under specific agronomical conditions.

ABA is a key phytohormone that plays pivotal roles in root growth. Accumulating evidence indicates that ABA regulates root growth through interaction with auxin. However, how ABA signaling is translated into auxin production to control root growth during adaptation to different soil environments is unclear. In the present study, we report that auxin acts downstream of ABA to inhibit root elongation and promote root swelling in response to soil compaction, and the ABA signaling transcription factor OsbZIP46 functions as a crosstalk node between ABA and auxin by directly activating the expression of auxin biosynthesis gene YUC8/REIN7. Our results unravel a molecular mechanism that bridges ABA signaling and auxin biosynthesis in primary root development, providing avenues for breeders to select crops resilient to soil compaction.

This work was funded by National Natural Science Foundation of China and the Agricultural Science and Technology Innovation Program of CAAS.

By Qin Hua (qinhua@caas.cn)